Method for preparing pressure-sensitive duplicating elements



Nov. 19, 1963 D. A. NEWMAN ETAL 3,111,421

METHOD FOR PREPARING PRESSURE-SENSITIVE DUPLICATING ELEMENTS Filed April 27. 1961 J0 rFA/SFER LAYER INVENTOR oaylas A. New/77am BY'T/omaS L. 'TL/Z@ HTTUJENEY@ United States Patent() 3,111,421 METHOD FOR PREPARENG PRESSURE-SENSETIVE DUPLICATNG ELEMENTS Douglas A. Newman, Glen Cove, N.Y., and Thomas L.

Tully, Bridgeport, Conn., assignors to Columbia Rihbon and Carbon Manufacturing Co., line., Glen Cove, NX., a corporation of New York Filed Apr. 27, 1961, Ser. No. 105,934 Claims. (Cl. 117-36.1)

IThis invention relates to novel methods for preparing pressure-sensitive duplicating elements including copy sheets and ytrans-fer sheets.

The use of transfer sheets of the so-called carbon paper type is one of the oldest and yet most currently employed systems for producing duplicate copies under the effects of imaging pressure as exerted for instance manually or by means of a typewriter.

There are two serious problems encountered through the use of such carbon papers, however, the first being the dirty surface of the transfer layers carried by carbon paper, and the second being the dirty, easily smudged images produced therewith.

. The first problem is of special importance to typists and the like who must handle carbon papers frequently and who must yet maintain cleanliness in the cop-ies being produced. The second problem is of special importance to anyone Iwho frequently handles and must frequently read carbon copies, but is of particular importance in the eld of automatic data processing by magnetic means. kAccording to this later field, carbon copies produced with magnetic pigment such as iron oxide and the like are automatically sensed, read or memorized through the use of a conventional magnetic reading head assembly, or other similar device which passes over the surface of the sheet or card being processed and produces electrical signlals when the magne-tized images pass thereunder. These electrical signals are completely depen-dent upon the quality of the images being sensed, and when this quality is disturbed through the images being smudged manually or by contact with the reading head assembly, then the automatic sensing equipment either bypasses the smudged images or reads -them incorrectly.

It is an object of the present invention to overcome these problems encountered through the use of conventional transfer sheets and ribbons of the carbon paper type.

It is an object of this invention to provide a novel method Ifor preparing transfer sheets and ribbons on which the transfer layer contains magnetic pigment and is exceptionally clean to the touch.

It is an object of this invention to provide a novel method for preparing transfer sheets and ribbons on which `the transfer :layer contains magnetic pigment and which produce smudge-resistant clean images under the effects of imaging pressure.

1I=t is another object of this invention to provide a novel method for preparing transfer sheets and ribbons on which the :transfer layer is exceptionally clean to the touch, has a Whiteor light-colored appearance and yet produces black colored images under the effects of imaging pressure.

These and other objects and advantages are accomplished according to the presen-t invention as more fully set out hereinafter.

3,111,421 Patented Nov. 19, 1963 ICS The present invention provides a novel method for preparing sheets and ribbons by dispersing a magnetic pigment such as black iron oxide in a suitable Wax or filmforming binder `material in conventional manner, applying the'binder-pigment composition to a suitable flexible foundation in conventional manner, and then while maintaining the applied composition in a fluid 4state passing the coated foundation over or under a magnet of sufficient strength to attract the magnetic pigment and cause it to migrate either :to the top or the bottom of the applied coating, depending upon the results desired. When the pigment has substantially completely migrated, the applied coating is solidified by cooling or by evaporation of the Isolvents present to set the magnetic pigment permanently in the location to which it has been attracted by the magnet.

In the drawing:

FIGURE 1 represents a diagrammatic cross-section, to an enlarged scale, of a transfer element according to lthis invention which is exceptionally clean to the touch,

demonstrating the nal location of the magnetic pigment and the position of the magnet employed to produce the transfer element.

lFlG. 2 represents a diagrammatic cross-section, to an enlarged scale, of a transfer element according to this invention which produces smudge-free clean images under the eliects of imaging pressure, demonstrating the final location of the magnetic pigment and the position of the magnet employed to produce the transfer element.

FIG. 3 is a diagrammatic cross-section, to an enlarged scale, of a smudge-free clean type-d image produced from the transfer element of FIG. 2.

FIG. 4 is a diagrammatic cross-section, to an enlarged scale, of a 'duplicating element wherein the binder coating used is a whiteor light-appearing porous blushed coating Wfhich substantially masks the color of Ithe underlying magnetic pigment.

The following examples are set forth by Way of illustration and should not be considered limitative.

Example 1 A trans-fer sheet according to FIG. 1 of the drawing was prepared as follows. A pressure-transfer composition was compounded by mixing the following ingredients in the approximate amounts specified:

Parts by Ingredients weight Carnauba Wax 50.0

Lanolin n-" 15.0 lMineral oil 20.0 Magnetic iron oxide 15.0

lthe magnetic pigment 11 and cause it to migrate to the bottom of the transfer layer 10 adjacent the paper foundation 20 and become overcoated with a relatively clear strata of the Wax binder composition 12. The coated sheet was then quickly cooled and set.

Sheets prepared in this manner are exceptionally clean to the touch since the surface of the transfer layer y10 is substantially completely f-ree of the black colored pigment.

Example 2 A transfer sheet accordin-g to FIG. 2 of the drawing was prepared as follows. A pressure-transfer composition was compounded by mixing the following ingredients in the approximate amounts specified:

Parts by Ingredients: weight Ethyl cellulose 7 Lard oil 8 Oleic acid 10 Magnetic iron oxide 16 =Filler (if desired) 4 Volatile solvent (toluol or the like) 5 The mixed solution was then coated onto a Mylar plastic foundation at room temperature in the absence of applied he-at, and while maintaining the applied coating fluid and at a low viscosity ydue to fthe presence of the solvent, the coated lm is passed under a magnet 50 of sufficient strength to attract the magnetic pigment 11 and cause it to migrate to the surface of the transfer layer -15 and form a pigment strata overlying the relatively clear strata of ethyl cellulose binder composition 13. The applied coating is then quickly solidified or set by heating slightly above room temperature to evaporate the volatile solvent.

Sheets prepared in this manner provide smudge-free clean images under the effects of imaging pressure. FIG. 3 illustrates one such image 16 carried on a copy sheet 21. The pigment 11 in the image is present adjacent to the copy sheet and is protected from smudging by a clean, substantially pigment-free supercoating of the binder composition l13. The term smudge-free is intended to mean that the pigment particles 1.1 are so protected as to be substantially completely immune from smearing or spreading on the copy sheet when the image makes contact with the han-ds or `with the head assembly o-f the sensing equipment. It should be understood that the clear vbinder supercoating 13 may spread under contact but that such spreading is not pigmented or dirty and thus will not interfere with the reliable automatic sensing of the images.

lI-n preparing transfer elements according to FIGS. 1 and 2 herein, use may be made of wax or film-forming binder systems interchangeably. Suitable wax binders include those conventional in the art such `as raw montan, beeswax, microcrystalline, Carbowax and the like, or mixtures thereof with eachother or with additives such as lanolin, petrolatum, ceresin or resinous materials. Suitable film-forming binder materials include the cellulose derivatives such as ethyl cellulose, methyl cellulose, hydroxyethyl cellulose, cellulose acetate and cellulose nitrate; vinyl resins such as vinyl chloride, vinyl acetate 'and copolymers thereof, polystyrene and polyvinyl stearate; chlorinated po'lyphenyl resins such as the Arochlors; polybutene resins such as Vista-nex Iand Indopol; and hydrophilic colloid materials such as `zein, gelatin, starch, carboxymethyl cellulose, -as Well as many others.

The wax binder transfer compositions are generally applied by hot melt methods although -in certain instances where resinous additi-ves are present, the composition may be 4applied through the use of a suitable volatile solvent such as carbon tetrachloride or the like. The lmforming binder compositions lare applied in the -form of a solution or dispersion of the binder and pigment in a suitable volatile solvent such as toluol, xylene, ethyl acetate, methyl ethyl ketone, ethanol, water or the dike, and mixtures thereof.

According to a further embodiment of this invention as illustrated by (FIG. 4 of the drawing, the layer 18 formed on the foundation 20' may be blushed in conventional manner to form surface strata 19 which masks and hides the black color of the underlying magnetic pigment 11. The formed layer 18 has been found to be pressuretransferable when it is coated onto a smooth plastic film foundation whereas it is not pressure-transferable when coated onto paper. Depending upon the nature of the yfoundation 20, therefore, the elements of FIG. 4 are either pressure-sensitive transfer sheets or pressure-sensitive copy sheets in which blushed coating 19 compresses and transparentizes under `imaging pressure to -allow the color of pigment particles 11 to become visible in the imaged areas. The following example illustrates the production of a transfer element.

Example 3 The 4following ingredients were mixed [in the approximate amounts specified:

Parts by IIngredients: Weight Ethyl cellulose 10 Carbowax 5 Methanol (solvent) 60 Water (non-solvent) 10 Magnetic iron oxide 15 The mixed solution was then coated onto a cellulose acetate plastic ilm at room temperature i-n the absence of applied heat, `and while the coating was maintained fluid the fil-m was passed over a magnet in the same manner outlined in Example 1. After the magnetic pigment 11 had migrated to the bottom of the transfer layer, heat was applied to evaporate the volatile alcohol and water and solidify or set transfer layer 18. The solidified layer 'was in the form of a blushed coating d-ue to the use of the non-solvent water which left the coating with a series of micropores. These micropores in the pigment-free supercoating 19 Igave the supercoating a whitish opaque appear-ance which masked and hid the black color of 4the underlying magnetic iron oxide. In sharp contrast to the light color of the transfer layer, sheets of this type produce black magnetic images lunder the effect of imaging pressure.

It should be understood that other conventional methods and ingredients lfor Aforming blushed coatings are contemplated by Ithis invention, the point of novelty herein being the use of magnetic pigment and magnetic means `for selectively locating said pigment.

Although black iron oxide is the preferred magnetic pigment used in the present invention, any other magnetic pigment such as iron powder, iron i-lings and the like may also be used.

There is no criticality with respect to the nature of the magnet used in the present process, the employment of permanent and electromagnets being contemplated. The magnet should be of sufficient intensity to attract the magnetic pigment and cause it to migrate through the fluid transfer layer. In some isntances where wax binders are used, it is convenient that the magnetic plate or rod also function as a heating device to keep the transfer layer fluid while simultaneously effecting pigment migration. Likewise, where necessary or advantageous, the use of a series of magnets is contemplated to insure more complete migration of the magnetic pigment.

Variations and modifications may be made within the scope of the claims and portions of the improvements may be used without others.

We claim:

1. The method of preparing a transfer element having a exible foundation carrying a pressure-transferable layer, said layer having two distinct strata, one of which is a relatively clear strata of binder material and the other of which is a strata of magentic pigment, which comprises applying to a flexible Vfoundation a uid transfer composition containing magnetic pigment dispersed in a binder material, exposing said fluid composition to a magnetic force of sufficient intensity to attract said pigment and cause it to migrate towards said magnetic force and form within said fluid transfer composition two distinct strata, one of which is a strata of magnetic pigment and the other of which is a relatively clear strata of binder material, and solidifying said transfer composition to form said transfer layer.

2. The method according to claim 1 in which the binder material comprises a wax and solidification of the transfer composition is effected by cooling.

3. The method according to claim 1 in which the binder material comprises a film-forming material dispersed in a volatile solvent and solidification of the transfer composition is effected by evaporation of said volatile solvent.

4, The method of preparing a transfer element having a flexible foundation carrying a pressure-transferable layer which is exceptionally clean to the touch, said layer having two distinct strata, one of which is a strata of magnetic pigment adjacent the foundation and the other of which is a relatively clear strata of binder material as a supercoating over said strata of magnetic pigment, which comprises applying to a flexible foundation a fluid transfer composition containing magnetic pigment clispersed in a binder material, exposing said fluid composition to a magnetic force applied against said foundation of sufficient intensity to attract said pigment and cause it to migrate towards said magnetic force and foundation and form within said fluid transfer composition two clistinct strata, one of which is a strata of magnetic pigment adjacent said foundation and the other of which is a relatively clear strata of binder material as a supercoating over said strata of magnetic pigment, and solidifying said transfer composition to form said transfer layer.

5. The method of preparing a transfer element having a flexible foundation carrying a pressure-transferable layer which provides smudgeproof clean images under the effects of imaging pressure, said layer having two distinct strata, one of which is a relatively clear strata of binder material adjacent the foundation and the other of which is a strata of magnetic pigment as a supercoating over said strata of binder mterial, which comprises applying to a flexible foundation a fluid transfer composition containing magnetic pigment dispersed in a binder material, exposing said fluid composition to a magnete force applied against the surface of said composition of suficient intensity to attract said pigment and cause it to migrate towards said magnetic force and said surface and form within said fluid transfer composition two distinct strata, one of which is a relatively clear strata of binder material adjacent said foundation and the other of which is a strata kof magnetic pigment as a supercoating over said` clear strata of binder material, and solidifying said transfer composition to form said transfer layer.

6. The method according to claim 5 in which the binder material comprises a wax and solidification of the transfer composition is effected by cooling.

7. The method according to claim 5 in which the binder material comprises a hlm-forming material dispersed in a voiatile solvent and solidification of the transfer composition is effected by evaporation of said volatile solvent.

8. The method of preparing a duplicating element having a fiexible foundation carrying a pressure-sensitive layer which is exceptionally clean to the touch, said layer having two distinct strata, one of which is a strata of magnetic pigment adjacent the foundation and the other of which is an opaque pressure-sensitive blushed coating which overlies and masks the color of the pigment strata, which comprises applying to a flexible foundation a fluid transfer composition containing magnetic pigment and a lm-forming binder material dispersed in a mixture of volatile components containing a volatile solvent for said binder material and a volatile non-solvent for said binder material, exposing said fluid composition to a magnetic force applied against said foundation of sufficient intensity to attract said pigment and cause it to migrate towards said magnetic force and foundation, and evaporating said volatile components to solidify said composition and form two distinct strata, one of which is a strata of magnetic pigment adjacent said foundation and the other of which is an opaque pressure-sensitive blushed coating of said binder material overlying and masking the color of the strata of magnetic pigment.

9. The method according to claim 8 in which the ilexible foundation is a smooth plastic film and the formed layer is pressuretransferablek 10. The method according to claim 8 in which the ilexible foundation is paper and the opaque blushed coating compresses and transparentizes under the effects of imagmg pressure.

References Cited in the file of this patent UNITED STATES PATENTS 2,313,810 Dalton Mar. 16, 1943 2,570,856 Pratt et al. Oct. 9, 1951 2,744,031 Mumma May 1, 1956 2,796,359 Speed June 18, 1957 2,912,344 Newman etal Nov. 10, 1959 3,020,172 Mohnhaupt Feb. 6, 1962 

1. THE METHOD FO PREPARIANG A TRANSFER ELEMENT HAVING A FLEXIBLE FOUNDATION CARRYING A APRESSURE-TRANSFERABLE LAYER, SAID LAYER HAVING TWO DISTINCT STRATA, ONE OF WHICH IS A RELATIVELY CLEAR STRATA OF BINDER MATERIAL AND THE OTHER OF WHICH IS A STRATA OF MAGENTIC PIGMENT, WHICH COMPRISES APPLYING TO A FLEXIBLE FOUNDATION A FLUID TRANSFER COMPOSITION CONTAINING MAGNETIC PIGMENT DISPERSED IN A BINDER MATERIAL, EXPOSING SAID FLUID COMPOSITION TO A MAGNETIC FORCE OF SUFFICIENT INTENSITY TO ATTRACT SAID JPIGMENT AND CAUSE IT TO MIGRATE TOWARDS SAID MAGNETIC FORCE AND FORM WITHIN SAID FLUID TRANSFER COMPOSITION TWO DISTINCT STRATA, ONE OF WHICH IS A STRATA OF MAGNETIC PIGMENT AND THE OTHER OF WHICH IS A RELATIVELY CLEAR STRATA OF BINDER MATERIAL, AND SOLIDIFYING SAID TRANSFER COMPOSITION TO FORM SAID TRANSFER LAYER. 